1. Field of the Invention
The invention relates in general to elevator systems, and more specifically, to elevator systems utilizing a buffer.
2. Description of the Prior Art
In elevator systems, it is required that a buffer be provided in the pit of the elevator hoistway to stop the elevator car in the event of overtravel. The buffer must accomplish this with a minimum of discomfort to the passengers and with a minimum of damage to the equipment. It is also common to provide a switch that is activated by movement of the buffer plunger and which acts to cut off power to the drive means whenever the plunger is in a retracted position. Once the elevator car has been moved away from the buffer, such as by a maintenance man using a switch override, the plunger is free to return to its restored position. If it fails to do so, the elevator should not be operated and further maintenance work is necessary. The switch operation has most recently been accomplished by a long cam mounted so that it moves in conjunction with the plunger in such a manner that when the plunger is in the retracted position, the cam contacts the switch sufficiently to operate it. When the elevator car moves away, the plunger normally returns to its restored position, allowing the switch to return to its original condition. In the event the plunger does not return to its restored position, the switch remains in its second condition and power is not restored to the drive, thus preventing a possibility of the elevator car later striking a retracted plunger. This type of construction is subject to alignment problems, however. The buffer plunger tends to exhibit rotational movement when struck by the elevator car, causing misalignment of the cam and the switch. Present methods used to preserve cam and switch alignment are often both costly and technically complicated.